1. Field of the Invention
The present invention relates to an anode material for a secondary battery, a method for producing the same and a secondary battery using the same, and more particularly to an anode material for a secondary battery capable of being used for a secondary battery producing process, which may improve a discharging capacity and a charging/discharging efficiency of battery by adjusting an amount of micropores inside the secondary battery, wherein the anode material for a secondary battery is produced by coating a high-crystallinity core carbonaceous material with a coating carbonaceous material and calcinating the high-crystallinity core carbonaceous material, a method for producing the same and a secondary battery using the same.
2. Description of the Related Art
Recently, there have been increasing demands for a small-sized and lightweight secondary battery having a relatively high capacity, and this trend has been accelerated as electronic apparatuses using a battery, for example portable phones, portable notebook computers, electric vehicles, etc., comes into wide use.
A high charging/discharging efficiency may be accomplished by a lithium ion secondary battery using a metal lithium as an anode material of the secondary battery, but the lithium ion secondary battery has a disadvantage that an internal short circuit may be caused since dendrite is formed while depositing a lithium ion onto a surface of the metal lithium upon charging. Due to the disadvantage, there has been proposed an alternative technology in which lithium alloys such as a lithium/aluminum alloy are used instead of the lithium metal. However, the lithium alloy have a disadvantage that a stable electrical property is not ensured if an alloy is used for an extended time due to segregation of the alloy caused when charge/discharge cycles are repeated for a long time. Meanwhile, a carbonaceous material having a high degree of carbonization was known as a promising material having an excellent charge/discharge cycle characteristic and a high stability of a battery since the carbonaceous material has a high charging/discharging efficiency, and a small voltage change upon discharging. However, the carbonaceous materials, including materials from graphite to amorphous carbon, have various structures and shapes, and therefore there have been proposed various shapes of carbonaceous materials having different properties according to physical properties or various microstructures of carbon since an electrode performance of the battery depends on the different physical properties and the various microstructures of the carbon. A lithium anode material for a secondary battery, used in recent years, includes carbon-based materials calcinated at approximately 1,000° C., and graphite-based materials calcinated at approximately 2,800° C. If the carbon-based materials are used as an anode material, the carbon-based materials have an advantage that an electrolyte is not dissolved due to a low reactivity to the electrolyte, while the carbon-based materials have a disadvantage that their potential changes are increased due to emission of lithium ions. Meanwhile, the graphite-based materials have an advantage that their potential changes are small due to emission of lithium ions, while the carbon-based materials have a disadvantage that they react to an electrolyte to dissolve the electrolyte, which may further destroy the electrode materials. As a result, a charging/discharging efficiency and a cycle characteristic of the battery are deteriorated, and a stability of the battery is damaged.
In order to solve the above-mentioned problems, there has been proposed a method for modifying a surface of a carbonaceous material, and as a result it was found that the surface-modified carbonaceous material having certain physical properties has an increased battery capacity and an improved cycle characteristics since reaction of the carbonaceous material with the electrolyte is inhibited. Accordingly, there have been attempts to develop a carbonaceous material capable of being used as an anode material of the secondary battery which can ensure an optimal battery characteristic, and the present invention was designed based on the above-mentioned facts.